[dm-devel] block: Fix a WRITE SAME BUG_ON

[John Dorminy]

On Thu, Jan 31, 2019 at 5:39 AM Christoph Hellwig <hch at infradead.org> wrote:
>
> On Wed, Jan 30, 2019 at 09:08:50AM -0500, John Dorminy wrote:
> > (I use WRITE_SAME to fill devices with a particular pattern in order
> > to catch failures to initialize disk structures appropriately,
> > personally, but it's just for convenience/speed.)
>
> How do you use it?  We don't have a user interface to generate
> REQ_OP_WRITE_SAME requests.

A not-checked-in test module, similar to Zhang Xiaoxu's reproducer,
exposing a sysfs node to trigger filling a block device with a test
pattern.